Coil Device

The present disclosure relates to a coil device. The present application claims priority based on Japanese Patent Application No. 2024-139652 filed on August 21, 2024. The entire contents of the Japanese Patent Application are incorporated herein by reference.

1 1 For example, Japanese Patent Laying-Open No. 2021-68828 (PTL) describes a coil device. The coil device described in PTLhas a substrate, and a first wound portion, a second wound portion, a third wound portion, and a fourth wound portion.

The substrate has a first main surface and a second main surface opposite to the first main surface. The first wound portion and the second wound portion are disposed on the first main surface. The third wound portion and the fourth wound portion are disposed on the second main surface. In each of the first wound portion, the second wound portion, the third wound portion, and the fourth wound portion, a wire is wound spirally in a plan view. The wire that forms the first wound portion is disposed alternately with the wire that forms the second wound portion in a direction from an inner circumference to an outer circumference of the first wound portion. The wire that forms the third wound portion is disposed alternately with the wire that forms the fourth wound portion in a direction from an inner circumference to an outer circumference of the third wound portion. An innermost circumference of the first wound portion is electrically connected to an innermost circumference of the third wound portion and an innermost circumference of the second wound portion is electrically connected to an innermost circumference of the fourth wound portion.

A coil device according to the present disclosure includes: a base film; a first wire; and a second wire. The base film has a first main surface and a second main surface. The first wire has a first wound portion disposed on the first main surface and a second wound portion disposed on the second main surface, each of the first wound portion and the second wound portion being a portion where the first wire is wound spirally in a plan view. The second wire has a third wound portion disposed on the first main surface and a fourth wound portion disposed on the second main surface, each of the third wound portion and the fourth wound portion being a portion where the second wire is wound spirally in a plan view. A portion of the first wire in the first wound portion is disposed alternately with a portion of the second wire in the third wound portion in a direction from an inner circumference to an outer circumference of the first wound portion, and overlaps a portion of the second wire in the fourth wound portion in a plan view. A portion of the first wire in the second wound portion is disposed alternately with a portion of the second wire in the fourth wound portion in a direction from an inner circumference to an outer circumference of the second wound portion, and overlaps a portion of the second wire in the third wound portion in a plan view.

1 There is room for improvement in inductance characteristics of the coil device described in PTL. The present disclosure provides a coil device with enhanced inductance characteristics. According to the coil device of the present disclosure, the inductance characteristics are enhanced.

First, an embodiment of the present disclosure will be listed and described.

(1) A coil device according to an embodiment includes: a base film; a first wire; and a second wire. The base film has a first main surface and a second main surface. The first wire has a first wound portion disposed on the first main surface and a second wound portion disposed on the second main surface, each of the first wound portion and the second wound portion being a portion where the first wire is wound spirally in a plan view. The second wire has a third wound portion disposed on the first main surface and a fourth wound portion disposed on the second main surface, each of the third wound portion and the fourth wound portion being a portion where the second wire is wound spirally in a plan view. A portion of the first wire in the first wound portion is disposed alternately with a portion of the second wire in the third wound portion in a direction from an inner circumference to an outer circumference of the first wound portion, and overlaps a portion of the second wire in the fourth wound portion in a plan view. A portion of the first wire in the second wound portion is disposed alternately with a portion of the second wire in the fourth wound portion in a direction from an inner circumference to an outer circumference of the second wound portion, and overlaps a portion of the second wire in the third wound portion in a plan view. According to the coil device in (1) above, inductance characteristics are enhanced.

(2) In the coil device in (1), the first wire may have a first external connection terminal and a first land that are disposed on the first main surface, and a second external connection terminal and a second land that are disposed on the second main surface. The first external connection terminal and the first land may be connected to an outermost circumference and an innermost circumference of the first wound portion, respectively. The second external connection terminal and the second land may be connected to an outermost circumference and an innermost circumference of the second wound portion, respectively. The first land and the second land may overlap each other in a plan view. The second wire may have a third external connection terminal and a third land that are disposed on the first main surface, and a fourth external connection terminal and a fourth land that are disposed on the second main surface. The third external connection terminal and the third land may be connected to an outermost circumference and an innermost circumference of the third wound portion, respectively. The fourth external connection terminal and the fourth land may be connected to an outermost circumference and an innermost circumference of the fourth wound portion, respectively. The third land and the fourth land may overlap each other in a plan view. According to the coil device in (2) above, a reduction in height can be achieved.

(3) In the coil device in (1) or (2), a distance between the portion of the first wire in the first wound portion and the portion of the second wire in the third wound portion that are adjacent to each other may be equal to or less than 20 m, and a distance between the portion of the first wire in the second wound portion and the portion of the second wire in the fourth wound portion that are adjacent to each other may be equal to or less than 20 m.

(4) In the coil device in (1) to (3), a width of the portion of the first wire in the first wound portion and a width of the portion of the first wire in the second wound portion may be equal to or less than 20 m. A width of the portion of the second wire in the third wound portion and a width of the portion of the second wire in the fourth wound portion may be equal to or less than 20 m.

100 Next, details of the embodiment of the present disclosure will be described with reference to the drawings. In the drawings below, the same or corresponding portions are denoted by the same reference characters and redundant description will not be repeated. A coil device according to the embodiment is referred to as a coil device.

100 A configuration of coil devicewill be described below.

1 FIG. 2 FIG. 1 FIG. 1 2 FIGS.and 3 FIG. 1 FIG. 1 2 3 FIGS.,and 100 100 20 20 30 100 10 20 30 is a first plan view of coil device.is a second plan view of coil deviceas seen from a direction opposite to that in. In, a wireis crosshatched in order to make a clear distinction between wireand a wire.is a cross-sectional view taken along III-III in. As shown in, coil devicehas a base film, wireand wire.

10 10 10 10 10 10 10 10 10 10 a b b a a b Base filmhas a main surfaceand a main surface. Main surfaceis a surface opposite to main surface. Main surfaceand main surfaceare end faces in a thickness direction of base film. Base filmis made of, for example, a flexible electrically-insulating material. Specific examples of the constituent material of base filminclude polyimide.

20 21 22 21 22 10 21 20 22 20 100 10 10 b a b Wirehas a first wound portionand a second wound portion. First wound portionis disposed on main surface 10a. Second wound portionis disposed on main surface. In first wound portion, wireis wound spirally in a plan view. In second wound portion, wireis wound spirally in a plan view. “In a plan view” refers to a case in which coil deviceis seen along a normal direction of main surfaceor a normal direction of main surface.

20 23 24 25 26 23 10 21 24 10 21 25 10 22 26 10 22 24 25 a a b b Wirefurther has a first external connection terminal, a first land, a second land, and a second external connection terminal. First external connection terminalis disposed on main surfaceand is connected to an outermost circumference of first wound portion. First landis disposed on main surfaceand is connected to an innermost circumference of first wound portion. Second landis disposed on main surfaceand is disposed in an innermost circumference of second wound portion. Second external connection terminalis disposed on main surfaceand is disposed in an outermost circumference of second wound portion. First landand second landoverlap each other in a plan view.

30 31 32 31 10 32 10 31 30 32 30 a b Wirehas a third wound portionand a fourth wound portion. Third wound portionis disposed on main surface. Fourth wound portionis disposed on main surface. In third wound portion, wireis wound spirally in a plan view. In fourth wound portion, wireis wound spirally in a plan view.

30 33 34 35 36 33 10 31 34 10 31 35 10 32 36 10 32 34 35 a a b b Wirefurther has a third external connection terminal, a third land, a fourth land, and a fourth external connection terminal. Third external connection terminalis disposed on main surfaceand is connected to an outermost circumference of third wound portion. Third landis disposed on main surfaceand is connected to an innermost circumference of third wound portion. Fourth landis disposed on main surfaceand is disposed in an innermost circumference of fourth wound portion. Fourth external connection terminalis disposed on main surfaceand is disposed in an outermost circumference of fourth wound portion. Third landand fourth landoverlap each other in a plan view.

20 21 30 31 21 21 20 21 20 21 20 21 A portion of wirein first wound portionis disposed alternately with a portion of wirein third wound portionin a direction from an inner side to an outer side of first wound portion. The direction from the inner side to the outer side of first wound portionrefers to a direction perpendicular to a direction in which the portion of wirein first wound portionextends in a plan view. When the portion of wirein first wound portionextends in a curved manner in a plan view, the direction in which the portion of wirein first wound portionextends is defined as a tangent direction of the curved portion.

20 22 30 32 22 22 20 22 20 22 20 22 A portion of wirein second wound portionis disposed alternately with a portion of wirein fourth wound portionin a direction from an inner side to an outer side of second wound portion. The direction from the inner side to the outer side of second wound portionrefers to a direction perpendicular to a direction in which the portion of wirein second wound portionextends in a plan view. When the portion of wirein second wound portionextends in a curved manner in a plan view, the direction in which the portion of wirein second wound portionextends is defined as a tangent direction of the curved portion.

20 21 30 32 20 22 30 31 20 20 30 20 10 20 30 20 30 The portion of wirein first wound portionoverlaps the portion of wirein fourth wound portionin a plan view. The portion of wirein second wound portionoverlaps the portion of wirein third wound portionin a plan view. From another point of view, in the portion where wireis wound spirally, wireis disposed to face wire, not wire, with base filminterposed therebetween. This relationship of overlapping between wireand wiremay only be satisfied at least in the portion where wireand wireextend linearly in a plan view.

20 21 1 20 22 2 30 31 3 30 32 4 1 3 21 2 4 22 1 4 A width of the portion of wirein first wound portionis denoted as a width W. A width of the portion of wirein second wound portionis denoted as a width W. A width of the portion of wirein third wound portionis denoted as a width W. A width of the portion of wirein fourth wound portionis denoted as a width W. Width Wand width Ware measured in the direction from the inner side to the outer side of first wound portion. Width Wand width Ware measured in the direction from the inner side to the outer side of second wound portion. Each of width Wto width Wis measured at arbitrary ten measurement points and is calculated as an average value of the measurement values at these ten measurement points.

20 21 30 31 1 20 22 30 32 2 1 21 2 22 1 2 A spacing between the portion of wirein first wound portionand wirein third wound portionthat are adjacent to each other is denoted as a spacing SP. A spacing between the portion of wirein second wound portionand wirein fourth wound portionthat are adjacent to each other is denoted as a spacing SP. Spacing SPis measured in the direction from the inner side to the outer side of first wound portionand spacing SPis measured in the direction from the inner side to the outer side of second wound portion. Each of spacing SPand spacing SPis measured at arbitrary ten measurement points and is calculated as an average value of the measurement values at these ten measurement points.

20 1 30 2 1 10 20 2 10 30 1 2 A height of wireis denoted as a height H. A height of wireis denoted as a height H. Height His a distance between the main surface of base filmand a top surface of wireand height His a distance between the main surface of base filmand a top surface of wire. Each of height Hand height His measured at arbitrary ten measurement points and is calculated as an average value of the measurement values at these ten measurement points.

1 4 1 2 1 2 Width Wto width Ware, for example, equal to or more than 4 μm and equal to or less than 20 μm. Spacing SPand spacing SPare, for example, equal to or more than 4 μm and equal to or less than 20 μm. Height Hand height Hare, for example, equal to or more than 4 μm and equal to or less than 50 μm.

20 30 41 42 43 Each of wireand wirehas, for example, a seed layer, an electroless plating layerand an electrolytic plating layer.

41 10 10 10 41 41 a b Seed layeris disposed on the main surface (main surface, main surface) of base film. A constituent material of seed layeris, for example, a nickel-chromium alloy. However, the constituent material of seed layeris not limited thereto.

42 42 41 10 41 24 25 34 35 42 24 25 34 35 42 42 Electroless plating layeris a layer formed by an electroless plating method. Electroless plating layeris disposed on seed layer. Although not shown, base filmand seed layerare provided with a first through hole and a second through hole. The first through hole overlaps first landand second landin a plan view. The second through hole overlaps third landand fourth landin a plan view. Electroless plating layeris also formed on an inner wall surface of the first through hole and on an inner wall surface of the second through hole. Thus, first landand second landare electrically connected to each other and third landand fourth landare electrically connected to each other. A constituent material of electroless plating layeris, for example, copper or a copper alloy. However, the constituent material of electroless plating layeris not limited thereto.

43 43 42 43 43 Electrolytic plating layeris a layer formed by an electrolytic plating method. Electrolytic plating layeris disposed on electroless plating layer. A constituent material of electrolytic plating layeris, for example, copper or a copper alloy. However, the constituent material of electrolytic plating layeris not limited thereto.

100 A method for manufacturing coil devicewill be described below.

4 FIG. 4 FIG. 100 100 1 2 3 4 5 6 7 is a diagram of a process for manufacturing coil device. As shown in, the method for manufacturing coil devicehas a preparation step S, a hole making step S, an electroless plating step S, a resist pattern forming step S, an electrolytic plating step S, a resist pattern removing step S, and an etching step S.

5 FIG. 5 FIG. 1 1 10 41 10 10 10 1 2 a b is an explanatory diagram of preparation step S. As shown in, in preparation step S, base filmis prepared. Seed layersare formed in advance on main surfaceand on main surfaceof base filmprepared in preparation step S1. After preparation step S, hole making step Sis performed.

2 10 41 2 3 In hole making step S, the first through hole and the second through hole are formed in base filmand seed layer. The first through hole and the second through hole are formed by laser processing or drill processing, for example. After hole making step S, electroless plating step Sis performed.

6 FIG. 6 FIG. 3 3 42 41 42 3 4 is an explanatory diagram of electroless plating step S. As shown in, in electroless plating step S, electroless plating layeris formed on seed layerby the electroless plating method. Although not shown, electroless plating layeris also formed on the inner wall surface of the first through hole and on the inner wall surface of the second through hole at this time. After electroless plating step S, resist pattern forming step Sis performed.

7 FIG. 7 FIG. 4 4 50 42 50 51 42 51 50 42 4 5 is an explanatory diagram of resist pattern forming step S. As shown in, in resist pattern forming step S, a resist patternis formed on electroless plating layer. Resist patternhas an opening. Electroless plating layeris exposed from opening. Resist patternis formed by attaching a dry film resist onto electroless plating layerand exposing the attached dry film resist to light and developing the attached dry film resist, for example. After resist pattern forming step S, electrolytic plating step Sis performed.

8 FIG. 8 FIG. 5 5 43 42 51 5 6 is an explanatory diagram of electrolytic plating step S. As shown in, in electrolytic plating step S, electrolytic plating layeris formed on a portion of electroless plating layerexposed from openingby the electrolytic plating method. After electrolytic plating step S, resist pattern removing step Sis performed.

9 FIG. 9 FIG. 6 6 50 42 6 7 is an explanatory diagram of resist pattern removing step S. As shown in, in resist pattern removing step S, resist patternis removed from electroless plating layer. After resist pattern removing step S, etching step Sis performed.

7 42 41 50 100 20 30 20 30 20 30 100 1 3 FIGS.to In etching step S, the portion of electroless plating layerand the portion of seed layerthat were located under resist patternbefore removal are removed by etching. In this way, in the method for manufacturing coil device, wireand wireare formed by a semi-additive method. A method for forming wireand wireis not limited thereto and wireand wiremay be formed by a subtractive method, for example. As described above, the structure of coil deviceshown inis formed.

100 200 300 An effect of coil devicewill be described below in comparison with coil devices according to comparative examples. A coil device according to a first comparative example is referred to as a coil device. A coil device according to a second comparative example is referred to as a coil device.

10 FIG. 11 FIG. 10 FIG. 12 FIG. 10 FIG. 10 11 12 FIGS.,and 200 200 200 10 20 30 200 100 is a first plan view of coil device.is a second plan view of coil deviceas seen from a direction opposite to that in.is a cross-sectional view taken along XII-XII in. As shown in, coil devicehas base film, wireand wire. In this respect, the configuration of coil deviceis the same as the configuration of coil device.

200 20 27 28 29 27 28 29 10 27 20 28 29 27 20 27 20 21 a In coil device, wirehas a fifth wound portion, a fifth external connection terminaland a sixth external connection terminal. Fifth wound portion, fifth external connection terminaland sixth external connection terminalare disposed on main surface. In fifth wound portion, wireis wound spirally in a plan view. Fifth external connection terminaland sixth external connection terminalare connected to an outermost circumference and an innermost circumference of fifth wound portion, respectively. The number of turns of wirein fifth wound portionis larger than the number of turns of wirein first wound portion.

200 30 37 38 39 37 38 39 10 37 30 38 39 37 30 37 30 31 b In coil device, wirehas a sixth wound portion, a seventh external connection terminaland an eighth external connection terminal. Sixth wound portion, seventh external connection terminaland eighth external connection terminalare disposed on main surface. In sixth wound portion, wireis wound spirally in a plan view. Seventh external connection terminaland eighth external connection terminalare connected to an outermost circumference and an innermost circumference of sixth wound portion. The number of turns of wirein sixth wound portionis larger than the number of turns of wirein third wound portion.

200 20 27 30 37 200 20 27 30 37 10 200 100 In coil device, a portion of wirein fifth wound portionoverlaps a portion of wirein sixth wound portionin a plan view. From another point of view, in coil device, the portion of wirein fifth wound portionfaces the portion of wirein sixth wound portionwith base filminterposed therebetween. In these respects, the configuration of coil deviceis different from the configuration of coil device.

200 20 30 100 100 200 29 10 39 10 a b In coil device, the number of turns of wireand the number of turns of wirethat are equivalent to those of coil devicecan be achieved with the same number of layers as that of coil device. However, in coil device, one (sixth external connection terminal) of the external connection terminals on main surfaceand one (eighth external connection terminal) of the external connection terminals on main surfaceare unavoidably disposed inside the wound portions.

200 10 10 20 30 10 29 39 200 200 a b Therefore, in coil device, an adhesive layer is disposed on main surface(main surface) to cover wire(wire), a base film different from base filmis disposed on the adhesive layer, and an external connection terminal electrically connected to sixth external connection terminal(eighth external connection terminal) is disposed on the base film. As a result, in coil device, coil devicehas a great height.

100 23 26 33 36 200 100 In contrast, in coil device, first external connection terminal, second external connection terminal, third external connection terminal, and fourth external connection terminalcan be disposed outside the wound portions. Therefore, unlike coil device, a reduction in height of coil devicecan be achieved.

13 FIG. 14 FIG. 13 FIG. 13 14 FIGS.and 15 FIG. 13 FIG. 13 14 15 FIGS.,and 300 300 20 20 30 300 10 20 30 300 100 is a first plan view of coil device.is a second plan view of coil deviceas seen from a direction opposite to that in. In, wireis crosshatched in order to make a clear distinction between wireand wire.is a cross-sectional view taken along XV-XV in. As shown in, coil devicehas base film, wireand wire. In this respect, the configuration of coil deviceis the same as the configuration of coil device.

300 20 21 20 22 30 31 30 32 300 100 In coil device, the portion of wirein first wound portionoverlaps the portion of wirein second wound portionin a plan view and the portion of wirein third wound portionoverlaps the portion of wirein fourth wound portionin a plan view. In this respect, the configuration of coil deviceis different from the configuration of coil device.

16 FIG. 17 FIG. 100 300 100 300 20 30 20 30 is a graph showing a relationship between a transmission loss in a differential mode and a frequency in each of coil deviceand coil device.is a graph showing a relationship between a transmission loss in a common mode and a frequency in each of coil deviceand coil device. The transmission loss in the differential mode refers to a transmission loss when AC signals of opposite phases flow through wireand wire, and the transmission loss in the common mode refers to a transmission loss when AC signals of the same phase flow through wireand wire.

16 17 FIGS.and 100 300 100 300 100 100 20 21 30 32 20 22 30 31 As shown in, the transmission loss in the differential mode in coil devicewas smaller than the transmission loss in the differential mode in coil device. In addition, although both of the transmission loss in the common mode in coil deviceand the transmission loss in the common mode in coil deviceincreased steeply at a specific frequency, the transmission loss in the common mode in coil devicechanged more steeply. These comparison results show that according to coil device, i.e., with the configuration in which the portion of wirein first wound portionoverlaps the portion of wirein fourth wound portionin a plan view and the portion of wirein second wound portionoverlaps the portion of wirein third wound portionin a plan view, impedance characteristics are enhanced.

It should be understood that at least one of the configurations and features described in the embodiments and examples can be combined with another embodiment and example, or can be modified in various manner.

Although the embodiment of the present invention has been described, it should be understood that the embodiment disclosed herein is illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.